Filter devices are used, for example, in motor vehicles. This can concern in particular air filter devices. Used therein is a filter element configured as an air filter.
For different applications in vehicles, so-called secondary air may be required. For example, an exhaust system can be equipped with an additional burner in order to heat up exhaust gas purification components during a warm-up phase to their operating temperature. Expediently, purified air is used as secondary air. In order to affect the operation of the internal combustion engine as little as possible, it is advantageous to extract the secondary air upstream of an air mass flow sensor, thus in particular already directly at the air filter device. In order to still be able to position the air mass flow sensor as close as possible to the filter element, comparatively high expenditure is required for implementing the secondary air port.